1. Field of the Invention
The present invention relates to a plasma display device, and more particularly, to a plasma display device and a driving method thereof.
2. Description of the Related Art
A plasma display device is a display device using a plasma display panel that displays text or images by using plasma produced by a gas discharge. A plurality of discharge cells is arranged on the plasma display panel in the form of a matrix.
The display panel of such a plasma display device is driven in a way that one frame is divided into a plurality of subfields having respective weight values. Furthermore, each subfield includes a reset period, an address period and a sustain period. The reset period is a period that initializes the discharge cells for stably performing an address discharge. The address period is a period that performs address discharges for selecting turned-on cells and non-turned-on cells from the display panel. Furthermore, the sustain period is a period that performs sustain discharges for displaying an image using the turned-on cells.
A conventional plasma display device applies a rising reset signal and a falling reset signal to scan electrodes so as to initialize the discharge cells during the reset period, applies a scan low signal to the scan electrodes for address discharges during the address period, and applies sustain signals to the scan electrodes for sustain discharges during the sustain period.
To this end, the conventional plasma display device includes a Vs voltage source which supplies a Vs voltage that is a high voltage and a Ypn switch coupled between the Vs voltage source and the scan electrode so as to apply a rising reset signal for increasing a voltage of the scan electrode to the Vs voltage (positive polarity voltage) during a rising period of the reset period to the scan electrode. The conventional plasma display device also includes a VscL voltage source which supplies a VscL voltage of a low voltage and a switch Yfr for a falling reset signal, and a switch YscL for a scan low signal which are coupled in parallel with each other between the VscL voltage source and the scan electrode. The switch Yfr is used to apply a falling reset signal for decreasing a voltage of the scan electrode from the Vs voltage to a Vnf voltage (negative polarity voltage) to the scan electrode during a falling period of the reset period, and the switch YscL is used to apply a scan low signal having a VscL voltage (negative polarity voltage) to the scan electrode during the address period.
As described above, in a conventional plasma display device, if the Ypn switch is turned off after a rising reset signal for increasing a voltage of the scan electrode to the Vs voltage during a rising period of the reset period is applied to the scan electrode, then a voltage Vs−VscL applied between the ends of both the switch Yfr for a falling reset signal and the switch YscL for a scan low signal that are coupled in parallel with each other between the scan electrode and the VscL voltage source is, for example, 200V−(−200V)=400V. Hence, the switch Yfr for applying the falling reset signal and the switch YscL for applying the scan low signal should be a switch whose withstanding voltage of Vs−VscL is, for example, 400V or more. However, such a switch having a high withstanding voltage is expensive, and thus it increases the manufacturing cost of a plasma display device.
Further, in order to facilitate an address discharge, a conventional plasma display device further includes a Zener diode which is coupled to the switch Yfr for a falling reset signal in series and is coupled to the switch YscL for a scan low signal in parallel so that a voltage of a falling reset signal is higher than a voltage of a scan low signal by more than a certain voltage. In other words, the Vnf voltage is higher than the VscL voltage by a certain voltage (that is, since a breakdown voltage of the Zener diode is the same as a certain voltage difference ΔV between a Vnf voltage and a VscL voltage, the Vnf voltage is higher than the VscL voltage by the breakdown voltage of the Zener diode.). As described above, because the Zener diode is positioned between the scan electrode and the VscL voltage source, a large current flowing between the scan electrode and the VscL voltage source passes through the Zener diode when the falling reset signal is applied to the scan electrode. Hence, a Zener diode having a high electric power, for example, 3 W or more should be used as the Zener diode through which a large current passes. However, a Zener diode having a high electric power is also expensive, and thus it increases the manufacturing cost of a plasma display device.